(1) Field of the Invention
This invention relates to improvements in isotope concentration systems for producing a substance enriched in desired isotopes of the elements hydrogen and/or oxygen.
(2) State of the Art
It has heretofore been known to produce a substance enriched in the heavy isotope of the element hydrogen having an atomic weight of 2 (i.e. deuterium), and/or in the heavy isotope of the element oxygen having an atomic weight of 18, by means of a two phase countercurrent contact isotope exchange concentrating process employing liquid water to supply the desired isotope and to serve either as one of said phases, or to replenish the isotope in the depleted phase where both of said two phases are other than water. Natural water contains a normal abundance of deuterium at about 1 part to 7,000 parts of protium having an atomic weight of 1 and oxygen-18 at about 1 part to 500 parts of oxygen-16 as well as oxygen-17 at about 1 part to 2,600 parts of oxygen-16. Such processes have accomplished isotope enrichment by reflux distillation, by mono-temperature chemical exchange of the isotopes of the element between a first substance and a reflux of another physically separable substance formed by chemical conversion from the first substance, or by dual temperature exchange of isotopes of the element between two physically separable substances containing said element. In all such processes the hydrogen or oxygen isotope produced has been supplied by liquid water from a natural source. Such knowledge is set forth in the publication "Production of Heavy Water" by George M. Murphy et al, McGraw-Hill Book Company, Inc., 1955, herein incorporated by reference, and hereinafter called "Murphy"; in the publication DP-400, "Production of Heavy Water, Savannah River and Dana Plants, Technical Manual, AEC Research and Development Report, July 1959, herein incorporated by reference and hereinafter called "DP-400"; and in Spevack U.S. Pat. No. 2,787,526,April 2, 1957, No. 2,895,803, July 21, 1959, and No. 3,860,698, Jan. 14, 1975, herein incorporated by reference, and hereinafter called Spevack '526, Spevack '803 and Spevack '698 respectively.
Since the heavy isotopes of hydrogen and/or oxygen exist only in minor proportions in the isotopic mixtures contained in natural water, all such enrichment processes have required handling of large quantities of water to obtain small quantities of product. As natural water usually contains dissolved mineral solids, its use has required either expensive pretreatment of the water, or the use of costly special equipment, construction, and/or materials, and/or processing, to cope with the problems incident thereto. Also, in the water-hydrogen sulfide dual temperature isotope exchange process for production of heavy water, as well as in other isotope enrichment processes utilizing valuable or hazardous water soluble substances, costly treatment of the waste streams of isotope depleted liquid water has been required to prevent loss of such substances and/or to avoid environmental pollution.